a. Field
The instant invention relates to a multi-phase modulator for a multi-phase power converter.
b. Background
A high performance multi-phase modulator (MPM) is a component in multi-phase power supplies. A number of previous approaches to realizing digital multi-phase modulators have followed the architecture of standard analog multi-phase pulse-width modulators (PWM) where a separate modulation ramp signal is generated for each phase, and the ramp signals are shifted in time by Ts/N, where fs=1/Ts is the per-phase switching frequency. An N-phase system requires N high-resolution digital pulse-width modulators, which limits the scalability of these approaches.
A different architecture, requiring a single high-resolution unit for an arbitrary number of phases has been described in R. F. Foley, R. C. Kavanagh, W. P. Marnane, and M. G. Egan, “A versatile digital pulsewidth modulation architecture with area-efficient FPGA implementation,” IEEE PESC 2005, pp. 2069-2615 and R. F. Foley, R. C. Kavanagh, W. P. Marnane, M. G. Egan, “Multiphase digital pulsewidth modulator, IEEE Trans. on Power Electron., vol. 21, no. 3, pp. 842-846, May 2006. This approach is based on the assumption that all phases operate with exactly the same duty cycle over each switching period Ts, and that the pattern of switching transitions for individual phases can be determined based on the duty-cycle command once per switching period Ts. This architecture leads to an efficient, scalable hardware realization, but limits the update rate to the switching frequency fs.